Why Thames A-Raters are the fastest dinghies on the River Thames (and why I want one)

 

Why Thames A-Raters are the fastest dinghies on the River Thames (and why I want one)

If you’ve ever been bimbling along on the Thames, feeling rather pleased with yourself because the boat is upright and nobody has fallen out, and then a Thames A-Rater goes past… you’ll know the sensation.

It’s a bit like being overtaken by a grand piano on rollerskates.

So what is an A-Rater, why are they so ridiculously quick on a river?

1) The “rule” that accidentally created a monster

A-Raters come from an old “rating rule” approach to racing, where the boat’s rating was basically calculated from waterline length and sail area—and that was largely it. Designers were given loads of freedom everywhere else.

Freedom + competitive sailors + the Thames = boats that are optimised like racing greyhounds.

Modern class rules still bake in the key performance ingredients: a maximum sail area (excluding spinnaker) of 350 sq ft, and on the Thames no spinnaker—because the river is narrow, twisty, and lined with things that enjoy eating rigs.
And the class parameters often quoted include a maximum mast height around 43 ft and a minimum weight around 750 lb (340 kg).

Translation: big rig, long boat, light enough to fly, built to go fast in the conditions we actually sail in.

2) Long waterline = fast “easy speed”

Even before the planing party starts, length matters. A longer waterline tends to mean a higher potential hull speed (and generally better speed through lulls). On the river, where you’re constantly dealing with shifting pressure, headers, and the occasional wind that appears to be coming from the direction of Slough, that “easy speed” is gold.

A-Raters are commonly described as around 27 ft long with towering rigs.
So while the rest of us are busy negotiating with physics, the A-Rater is already halfway to the next bend looking smug.

3) Sail area that looks slightly illegal (but isn’t)

Put simply: they carry a lot of sail for their weight.
That means acceleration—proper, shove-you-in-the-back acceleration.

On a river, acceleration matters more than people think, because you’re constantly changing mode:

• accelerating out of a tack

• punching through a lull

• dodging a hole behind trees

• then accelerating again because the wind has decided to move house

A-Raters are basically built for that stop-start, bendy-river reality.

4) Hull shape made for river sailing (and occasional flight)

These boats have a specialist Thames heritage and a design lineage tied to the conditions at places like Thames Sailing Club and Upper Thames.
They’re often described as scow-hulled with a metal centreplate, and famously quick—able to plane readily, but also technically demanding when it’s breezy.

That “scow + big rig” combination is a lovely cheat code:

• powerful in light to medium airs

• stable enough to carry that sail plan

• and when the breeze is on, they can pick up and go properly fast

5) The Thames factor: narrow, shifty, and full of surprises

If you designed a boat purely for steady sea breeze and open water, it might be brilliant… somewhere else.

But on the Thames:

• the wind bends around trees, houses, bridges, and moored boats

• the course can be tight, tactical, and full of rapid manoeuvres

• and you need boats that can keep moving through chaos

A-Raters were born in exactly this environment and refined over generations. That’s why they look like they belong in a sepia photograph… right up until they light up and leave everything else looking parked.

6) Why I want one (the honest bit)

There are sensible reasons, and there are the real reasons.

Sensible reasons:

• They’re a living piece of Thames sailing history (and still actively raced).

• They are, genuinely, among the most exciting boats you’ll see on the river—fast, elegant, and technical.

• There’s a proper community around them, with sailing at places close to me (including Upper Thames Sailing Club).

Real reasons:

• They look magnificent. Not “nice boat” magnificent. More “Victorian engineering meets modern adrenaline problem” magnificent.

• I like learning things that are hard. And A-Raters are described as technically highly challenging when it’s above moderate wind.

• Deep down, I want to experience that moment when you get it right—trim set, plate set, balance right—and the boat just… releases and goes.

Also, let’s be honest: if you’ve spent any time at Upper Thames watching A-Raters, at some point you start thinking:
“I could do that.”
This is the exact same thought process that leads people to buy paddleboards, telescopes, and bread makers.

7) The “small print” (aka: why this is a long-term dream)

A-Raters are not “buy one and go for a casual potter” boats. They’re typically sailed with a crew of three, and they demand teamwork and practice.
They also have serious rigs, serious loads, and serious consequences if you treat them casually.

So yes, I want one. But I also want to earn one:

• more river racing experience

• more boat handling time in breeze

• more time understanding what makes fast boats fast (and what makes them suddenly not)

In other words: I’m not in a rush. I’m just… planning. Constantly. Loudly. In public.

8) If you want to fall down the A-Rater rabbit hole

I’ve gathered more background, history, and boat info here:https://pmrsailing.uk/Raters/Rater-Boat-Info.html
And if you want the broader class/association side (including “try a rater” days), the Thames A-Rater Association is the place to start or come to the Upper Thames Open Days where you can go out in a Rater and see for yourself.